Method and apparatus for recording a single video frame

Abstract

A disc recorder having a single magnetic pick-up and record head and having a magnetic disc, rotating at the frame rate of a video signal, records and provides for display of a single frame from a video signal consisting of a series of video frames. Motion jitter is eliminated by recording on the disc recorder one of the two fields which make up a chosen video frame and then reproducing this field. The reproduced field signal is then stored and rerecorded onto the magnetic disc at a position relative to the original field recording corresponding to the delay between two interlaced fields. A memory having less capacity than that required for storing a complete field signal is used with only a portion of a field being reproduced, stored and rerecorded during each rotation of the magnetic disc. A complete video frame is thus recorded, ready for display, in which the two interlaced fields are identical.

What is claimed is: 
     
       1. A method of developing a frame signal from a video signal comprised of a succession of frames, each frame including two interlaced fields, comprising the steps of: recording a single frame signal on a disc recorder, said disc recorder including a single transducer and a magnetic disc rotating at the rate of one rotation for each frame in said succession of frames,   producing one field signal of the recorded frame signal with said transducer and storing said field signal,   rerecording the stored single field signal on said disc recorder, and   reproducing the two field signals recorded on said disc recorder whereby a frame signal consisting of two identical interlaced fields is provided.   
     
     
       2. The method of claim 1 further comprising the step of supplying said two field signals which were recorded on said disc recorder to a monitor whereby a frame consisting of two identical interlaced fields is displayed. 
     
     
       3. The method of claim 2 in which only a portion of said one field signal including an integral number of lines is reproduced, stored and rerecorded during each rotation of said magnetic disc whereby a plurality of rotations of said disc recorder are required prior to reproducing the two field signals and supplying said signals to a monitor. 
     
     
       4. A method of developing a single frame video signal from a video signal consisting of successive frames, each of said successive frames consisting of two interlaced fields, and recording said single frame video signal on a recorder having a moving magnetic medium and a single stationary transducer, said transducer defining an endless recording track on said medium during a complete cycle of movement of said magnetic medium, comprising the steps of: applying a single field signal to said transducer and recording said single field signal on said recording track,   sensing the recorded single field signal with said transducer and supplying said single field signal to a memory,   storing said single field signal in said memory,   reading out said single field signal from said memory and reapplying said single field signal to said transducer, and   rerecording said single field signal on said recording track at a position on said track corresponding to the time delay between two interlaced fields, whereby said single field signal is recorded twice on said recording track and positioned so that the two recordings of said single field signal are interlaced to comprise a single frame signal.   
     
     
       5. A method of developing a single frame video signal from a video signal consisting of successive frames, each of said successive frames consisting of two interlaced fields and each of said fields consisting of a plurality of lines, and recording said single frame video signal on a recorder having a moving magnetic medium and a single stationary transducer, said transducer defining an endless recording track on said medium as said medium moves past said transducer, comprising the steps of: a. applying a single field signal to said transducer and recording said single field signal on said recording track,   b. sensing a portion of the recorded single field signal with said transducer, said portion including an integer number of said plurality of lines,   c. storing the sensed portion of said single field signal,   d. rerecording said sensed portion of said single field signal on said medium at a location on said recording track with respect to the portion of the sensed portion of said single field signal corresponding to the time delay between the initiation of two successive fields, and   e. repeating steps (b), (c) and (d) for successive portions of said single field signal until said single field signal is rerecorded in its entirety on said recording track in a position such that said single field signal comprises the interlaced fields of a video frame signal.   
     
     
       6. A stop-action recorder for recording a video signal and for providing at a frame rate to a monitor a video frame composed of two interlaced fields, without the motion jitter that results from spatial displacement of a subject during the time between display of the two interlaced fields, comprising: video source means for providing a signal to be recorded;   disc means, including a magnetic disc and a magnetic pick-up and record head adjacent said magnetic disc, for recording a video signal;   means for rotating said disc at the rate of one revolution per frame;   memory means for storing a signal applied thereto;   switch means for applying one of said two interlaced field signals to said disc means to be recorded on said magnetic disc during one-half revolution of said disc;   means, connected to said head, for reproducing said one of said two interlaced field signals recorded on said magnetic disc and for applying the reproduced field signal to said memory means; and   means, connected to said memory means, for reapplying said reproduced field signal to said switch means whereby said one of said two interlaced fields is rerecorded by said disc means such that, in a subsequent display of the signal recorded on said disc means, a frame composed of two identical interlaced fields will be shown by a video monitor.